(1) Field of the Invention
The present invention relates, in general, to the authentication of media. More specifically, the present invention provides methods for authenticating papers and other media, a process for producing counterfeit-resistive items, counterfeit-resistive items, and an apparatus for authenticating documents and other media.
(2) Description of Related Art
The issues of authentication and counterfeit deterrence can be important in many contexts. Bills of currency, stock and bond certificates, credit cards, passports, bills of lading, as well as many other legal documents (e.g., deeds, wills, etc.) all must be reliably authentic to be useful. Authentication and avoidance of counterfeiting can also be important in many less obvious contexts. For example, improved verification/counterfeiting prevention mechanisms would he very useful in, for example, verifying the contents of shipping containers, quickly identifying individuals with particular health or criminal histories, etc.
A wide variety of attempts have been made to limit the likelihood of counterfeiting. For example, some have tried to assure the authenticity of items by putting coded or uncoded markings thereon (e.g., an artist's signature on his or her painting). Unfortunately, as soon as the code is broken--e.g., a counterfeiter learns to duplicate a signature, this method becomes worthless for authentication purposes. In the context of paper products (e.g., currency), counterfeiting-prevention methods have also used two-dimensional authentication mechanisms--e.g., watermarks or special threads incorporated within the paper used to make the currency. These mechanisms are clearly helpful, but they can also be overcome. For example, counterfeiters routinely bleach a one dollar bill (in such a way that the colored threads which mark the special currency paper are not damaged) and then imprint the markings of a one-hundred dollar bill thereon.
Other authentication methods have utilized mechanisms which provide three dimensions of data. For example, the holograms provided on many credit cards provide more variables (i.e., relative to two-dimensional threads or watermarks) which may be precalibrated, and thereafter, used to verify the authenticity of an item. Nevertheless, since holograms have a pre-set, or deterministic, pattern they may also be duplicated, and counterfeit products made. Authentication mechanisms which utilize deterministic patterns are inherently vulnerable to counterfeiting since the counterfeiter, in essence, has a "fixed" target to shoot at. This is the reason that military codes are frequently changed. At the other end of the spectrum, a random authentication mechanism would provide an incessantly "moving" and nonrepeating target which would be practically impossible to duplicate.
Finally, although existing authentication mechanisms provide adequate protection against counterfeiting in some contexts, increasingly valuable documents require increasingly reliable levels of authentication. Furthermore, current counterfeiters have access to extremely powerful tools--e.g., color photocopying equipment, reverse engineering of semiconductor chips, etc. These factors have combined to provoke strong demand for new methods and mechanisms for authenticating items, especially methods and mechanisms which are less vulnerable to counterfeiting.